U.S. patent number 4,095,064 [Application Number 05/727,273] was granted by the patent office on 1978-06-13 for paddle for use in a rotating-paddle bin level indicator.
This patent grant is currently assigned to Bindicator Company. Invention is credited to Paul P. Fleckenstein.
United States Patent |
4,095,064 |
Fleckenstein |
June 13, 1978 |
**Please see images for:
( Certificate of Correction ) ** |
Paddle for use in a rotating-paddle bin level indicator
Abstract
Apparatus for indicating the level of flowable material in a
storage bin comprising a motor rotatably suspended within a
protective enclosure and having a driveshaft directly coupled to a
paddle disposed within the bin to engage material therein. A nipple
extending from the enclosure is threadably received within a gland
carried by a bin wall with the paddle extending into the bin space.
The paddle comprises a hollow tube curved at a fixed radius over an
arc of substantially ninety degees, and then flattened or pinched
at one end thereof over an arc of about fifty degrees to form a
closed bill which may be inserted through the mounting gland.
Inventors: |
Fleckenstein; Paul P. (Port
Huron, MI) |
Assignee: |
Bindicator Company (Port Huron,
MI)
|
Family
ID: |
24922010 |
Appl.
No.: |
05/727,273 |
Filed: |
September 27, 1976 |
Current U.S.
Class: |
200/61.21 |
Current CPC
Class: |
G01F
23/226 (20130101) |
Current International
Class: |
G01F
23/22 (20060101); H01H 035/00 () |
Field of
Search: |
;200/61.2,61.21 ;340/24C
;259/106,108 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Scott; James R.
Attorney, Agent or Firm: Barnes, Kisselle, Raisch &
Choate
Claims
The invention claimed is:
1. In a material bin level indicator of the type comprising an
indicator housing having a mounting nipple extending therefrom
adapted to engage a corresponding gland on a bin wall for mounting
said housing, a motor carried within said housing and operatively
coupled to a driveshaft having an axis of rotation extending
through said nipple, and a paddle operatively coupled to and
extending from said shaft to a free end of said paddle; the
improvement wherein said paddle comprises a curved hollow
cylindrical tube having a tubular portion adjacent said shaft and a
flattened portion comprising opposed tube walls flattened in a
plane coplanar with said axis and flaring into said tubular
portion, and means disposed within said tubular portion for
coupling said paddle to said shaft, both said tubular and said
flattened portions being curved at fixed radius from adjacent said
coupling means over an arc of substantially ninety degrees, said
flattened portion extending over substantially fifty degrees of
said arc and terminating at said free end, said paddle being
dimensioned such that the same may be inserted into a bin through
the mounting nipple while said paddle is coupled to said shaft.
2. The apparatus set forth in claim 1 wherein said paddle is formed
of stainless steel material.
3. The apparatus set forth in claim 1 wherein said paddle is formed
of resilient material.
4. The apparatus set forth in claim 3 wherein said resilient
material is synthetic rubber.
Description
BACKGROUND OF THE INVENTION
The present invention relates to bin level indicators and, more
particularly, to improvements in apparatus of the rotating paddle
type for indicating the level of flowable material in a storage
tank or bin. Specifically, the invention relates to an improved
paddle for use in apparatus of the referenced type.
Bin level indicators of the above-referenced type typically
comprise a motor carried for limited rotation within a protective
enclosure and connected to a rotatable paddle which is adapted to
engage flowable material within a storage bin when the material
rises to the bin level at which the rotating paddle is disposed.
The material drag on the paddle causes the motor drive torque to
rotate the motor rather than the paddle, which rotation is normally
sensed by one or more switches carried within the enclosure. The
switches may be connected to deactivate a conveyor feeding material
to the bin, or to perform other control functions related to
material level. Two examples of bin level indicators of the
described type are shown in Grostick U.S. Pat. No. 2,851,553 and
Gruber U.S. Pat. No. 3,542,982.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved
rotating paddle bin level indicator which is more economical to
fabricate and assemble than are prior art indicators of similar
type.
It is a specific object of the present invention to provide an
improved paddle for a rotating-paddle bin level indicator which is
adapted to be inserted into a material bin through a relatively
small indicator mounting gland, and is thus of the type shown in
the prior art U.S. Pat. Nos. to Obenshain 2,680,298, Murphy
3,322,403 and Donaldson 3,436,059, as well as in the
above-mentioned Gruber patent.
BRIEF DESCRIPTION OF THE DRAWINGS
The novel features which are considered to be characteristic of the
present invention are set forth in particular in the appended
claims. The invention itself, however, together with additional
objects, features and advantages thereof, will be best understood
from the following description when read in conjunction with the
accompanying drawings in which:
FIG. 1 is an elevational view, partly in section, showing a
presently preferred embodiment of the bin level indicator provided
by the invention;
FIG. 2 is a sectional view taken along the line 2--2 of FIG. 1;
FIG. 3 is a sectional view taken along the line 3--3 of FIG. 2;
FIGS. 4 and 5 are sectional views taken along the lines 4--4 and
5--5 of FIG. 3, respectively; and
FIGS. 6 and 7 are respective side and end views of the improved
paddle provided by the invention and shown in FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings, the preferred embodiment 10 of the bin
level indicator provided herein includes two plastic
injection-molded hemispheres 12,14 threaded at their respective
open rims and adapted to be interengaged to form a compact
spherical housing 16. An annular resilient O-ring 18 (FIG. 2) is
crushed between the rims of respective hemispheres 12,14 upon
threaded interengagement thereof to seal the internal structure of
indicator 10 from the outside atmosphere. A hollow externally
threaded nipple 20 is formed at the zenith of hemisphere 12, and is
adapted to be threadably received in a corresponding internally
threaded gland 22 carried by the wall of a material storage tank or
bin 24 (FIG. 1). An internally threaded hole 26 (FIG. 3) is formed
adjacent the rim of nippled hemisphere 12 to receive a strain
relief grommet 28 (FIG. 1), through which is fed a multiconductor
electrical cable 30 adapted for connection to level indicating
apparatus disposed within housing 16. A flat or plane region 32,
upon which indicator 10 may be rested during storage, is formed on
the outer surface of hemisphere 14 at the zenith thereof.
Internally, indicator 10 includes a molded plastic switch bracket
34 (FIGS. 2 and 3) centrally bridging, and mounted by means of
screws 36,37 received into correspondingly threaded openings in the
shoulders 38,39 adjacent to the open rim of nippled hemisphere 12.
Switch bracket 34 comprises a pair of generally rectangular switch
cups 40,42 molded at respective ends of bracket 34 and adapted to
receive by press-fit a pair of conventional electrical switches
44,46 having preselected outside rectangular geometries. A bridge
48 connects bracket switch cups 40,42, and has mounted thereon
remotely of nipple 20 a terminal block 50 for electrical
interconnection of the internal indicator components to external
monitoring and control circuitry (not shown) via cable 30 (FIG. 1).
Switch bracket 34 is fabricated such that bridge 48 is recessed
with respect to the open ends of switch cups 40,42 to minimize the
possibility of wires or terminals on block 50 touching the inside
of opposing hemisphere 14. This feature will be discussed in
greater detail hereinafter.
A AC motor 52 having an eccentrically-carried driveshaft or rotor
54 is suspended from switch bracket 34 by means of an axially
extending projection 56 of shaft 54 being press-fitted into a
corresponding cup 58 integrally formed on the underside of bracket
bridge 48. A generally symmetrical switch-actuating cam plate 60
(FIGS. 2, 3 and 4) is carried by and extends radially from
respective sides of motor 52 for cooperative engagement between
oppositely disposed cam surfaces 62,64 on bracket 60 and respective
bracket-mounted switches 44,46. Switches 44,46 include actuator
arms 66,68 extending through corresponding apertures in the bases
of switch cups 40,42, and terminating in roller followers 70, 72
adapted to follow the contour of respective cam surfaces 62,64 as
the motor and cam plate are rotated, the electrical condition of
each respective switch being responsive to the position of the
associated follower on the opposing cam surface. Cam surfaces 62,64
include radially opposed lower and upper flat dwell portions 74, 76
(FIGS. 3 and 4) at the respective ends of the follower ramps 78 so
that motor 52 and cam plate 60 may rotate slightly in response to
transient bin conditions without changing the states of respective
switches 44,46. A coiled return spring 80 has one end hooked
through an aperture 81 in cam plate 60 (FIG. 4) and the other end
held in fixed position relative to the cam plate in an aperture 83
(FIG. 5) in hemisphere shoulder 38. A projecting dog 79 is formed
on cam surface 64 and cooperates with hemisphere shoulder 39 to
provide a stop, and to thus limit corotation of motor 52 and cam
plate 60.
A driveshaft 82 (FIG. 2) has a flat blade-like projection 84
received and pinned in a corresponding fitting 86 at the outer end
of motor shaft 54. Shaft 82 extends from fitting 86 through a pair
of axially spaced thrust washers 88,90 carried within mounting
nipple 20, and through a sleeve bearing 92 disposed between thrust
washers 88,90, respectively. A pair of grip rings 94,96 retain
washers 88,90 in abutting relation to opposed ends of sleeve
bearing 92. A protective lip seal 97 surrounds shaft 82 within
mounting nipple 20. Indicator 10, as thus far disclosed, is the
subject of the copending application of Patrick L. Briggs, Ser. No.
727,274 now abandoned filed concurrently herewith and having a
common assignee.
As best seen in FIGS. 6 and 7, the paddle 100 provided in
accordance with the present invention comprises a hollow
cylindrical tube curved at a fixed radius over an arc of
substantially ninety degrees, and then flattened or pinched at one
end thereof over an arc of about 50.degree. such that opposed
flattened tube walls 103,105 form a closed bill 104 coplanar with
the tube axis. Flattened walls 103,105 flare at 107,109 into an
unpinched portion 111 of the curved tube which, in turn, is
contiguous with the open cylindrical tube end 106. A coupler
fitting 102 is inserted into open tubular end 106 of paddle 100 and
adhered thereto by one or more spot welds around the outer tube
circumference. Fitting 102 is received over the projecting end of
driveshaft 82, and is mounted thereto by a pin 108. The raw tube
stock for paddle 100 is preferably selected such that the maximum
width of the arched paddle, i.e., the width of bill 104, is small
enough to be inserted through gland 22 (FIG. 1). Paddle 100 is
preferably formed of stainless steel. Alternatively, paddle 100 may
be formed of slightly resilient material, such as synthetic rubber.
The alternative paddle material is particularly useful where it is
anticipated that stored material may be poured or splashed upon the
paddle, in which circumstance the resiliency of the paddle will
absorb the shock of material contact, and thus help prevent false
level indications.
To mount indicator 10 to bin 24, paddle 100 is first pinned to
driveshaft 82, either at the factory or at the bin site, and
hemispheres 12,14 are threadably disengaged. Paddle 100 is then
inserted through gland 22, and nipple 20 is threaded into the gland
to fixedly mount hemisphere 12 to the bin wall. With hemisphere 14
detached, cable 30 (FIG. 1) is then fed through strain relief
grommet 28, and the various conductors in the cable are connected
to appropriate terminals of the internal apparatus. For example,
the conductors of cable 30 providing motor-drive current are
conducted to the terminals of terminal block 50. Similarly, the
cable conductors which are to carry the information of bin level
condition are connected to appropriate terminals of switches 44,46
best seen in FIG. 5. Seal 18 and hemisphere 14 are then fitted over
and threadably engaged with hemisphere 12, and the bin level
indicator 10 is ready for operation.
In operation, power is continuously applied to motor 52 providing
drive torque to shaft 82 and paddle 100. If the material is below
the level of the paddle, the paddle will freely rotate, and motor
52 and cam plate 60 will be biased by spring 80 into the normal
positions thereof indicated in the drawings. When the material in
bin 24 rises to the level of paddle 100, the material exerts a drag
on the paddle retarding rotation thereof. With paddle 100 thus held
in fixed position, the drive torque developed by motor 52 overcomes
the force of return spring 80, and causes corotation of the motor
and cam plate 60 about the axis of motor shaft 54 against the force
of return spring 80. Such rotation is continued over an arc
sufficient to actuate switches 44,46, until stop 79 abuts
hemisphere shoulder 39. The motor and paddle are then both held in
fixed position relative to the shaft axis by stop 79 and the motor
is stalled until such time as the material no longer blocks
rotation of the paddle, whereupon the paddle is again free to
rotate and the motor and attached cam plate are returned by spring
80 to the positions depicted in the drawings.
The several advantages of the indicator herein described will be
evident from the foregoing description. For example, switches
44,46, terminal block 50 and motor 52 may be purchased as
off-the-shelf components. Hemispheres 12,14, bracket 34 and cam
plate 60 are each preferably formed of relatively inexpensive
injection-molded plastic material. Moreover, in the indicator
herein described, the need for some of the more expensive component
parts and assemblies of prior art bin level indicators has been
eliminated. For example, in the described indicator, the
conventional roller bearing for journaling rotation of the output
driveshaft has been replaced by a relatively less expensive sleeve
bearing 92. Similarly, the preferred AC motor 52 not only replaces
the relatively more expensive gear-drive motor indicative of the
prior art, but because the AC motor may be held in the stalled
condition for a relatively long period of time without sustaining
permanent damage, motor 52 may be coupled through a direct drive
connection to paddle 100, i.e., by shaft 82, rather than through
the usual clutch mechanism as in the prior art.
The disclosed indicator also has several, perhaps more subtle,
advantages over prior art bin level indicators of the rotating
paddle type. For example, by locating bridge 48 in recessed
position relative to the open ends of switch cups 40,42, the
terminals of block 50 are separated from the opposing inside
surface of hemisphere 14 by a substantial air gap, such that the
usual cardboard insulator cover for the terminal block need not be
provided. Moreover, in the preferred form of the invention, the
hemispheres 12,14 are formed of insulating material, i.e., plastic,
so that even if any of the internal leads or terminals should touch
the opposing inside wall of the housing, such lead or terminal will
be insulated for electrical ground by the housing itself. Paddle
100 provided by the invention herein is economical to fabricate,
and the preferred stainless steel embodiment of the paddle has
exhibited satisfactory strength characteristics without the use of
the strengthening corrugations required in the paddle disclosed in
the above-referenced Gruber patent.
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